Antiglare substrate and method of manufacturing the same

Abstract

To provide an antiglare substrate that can compatibly suppress reflection of external light and also suppress deterioration in visual clarity, and also has superior visibility.SOLUTION: An antiglare substrate 1 has a principal surface (first principal surface 1a) and also has antiglare properties on the principal surface, and comprises a glass substrate. The thickness is 0.05 to 1 mm, an uneven part 2 is provided on at least a part of the principal surface, and an arithmetic average height Sa of a contour curved surface of the uneven part 2 is 0.1 to 0.5 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antiglare substrate, which is a substrate having antiglare properties, and a method for producing the same. [Background technology]

[0002] Cover members such as cover glass are widely used in displays for mobile phones, tablet devices, televisions, digital signage, and the like. The visibility of such displays can be degraded by reflections of external light, etc. Therefore, various attempts have been made to improve the visibility of displays. For example, Patent Document 1 below discloses a glass article in which an anti-glare layer is provided on a transparent substrate. By providing the anti-glare layer, reflections of external light on the glass article are suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-106014 Summary of the Invention [Problem to be solved by the invention]

[0004] When a glass article provided with an anti-glare layer is used as a cover glass for a display or case, reflection of external light is suppressed. However, the clarity of the image seen through the glass article, i.e., the resolution, may decrease, and glare may become more noticeable.

[0005] An object of the present invention is to provide an antiglare substrate that can suppress both the reflection of external light and the deterioration of visual clarity, and that has excellent visibility, and a method for producing the same. [Means for solving the problem]

[0006] Various aspects of the antiglare substrate that solve the above problems will be described below.

[0007] An anti-glare substrate according to aspect 1 of the present invention has a main surface and exhibits anti-glare properties on the main surface, the anti-glare substrate comprising a glass substrate and having a thickness of 0.05 mm or more and 1 mm or less, wherein an uneven portion is provided on at least a portion of the main surface, and the arithmetic mean height Sa of the contour curved surface of the uneven portion is 0.1 μm or more and 0.5 μm or less.

[0008] The antiglare substrate of the second aspect is preferably the antiglare substrate of the first aspect, which is made of only the glass substrate.

[0009] The antiglare substrate of aspect 3 is preferably the same as that of aspect 1 or 2, except that the glass substrate is made of alkali-free glass.

[0010] In the antiglare substrate of aspect 4, in any one of aspects 1 to 3, it is preferable that the kurtosis Sku of the contour curved surface of the concave-convex portion is 0 or more.

[0011] In the antiglare substrate of aspect 5, in any one of aspects 1 to 4, it is preferable that the skewness Ssk of the contour curved surface of the concave-convex portion is less than 0.

[0012] The antiglare substrate of the sixth aspect is preferably used as a cover member for a medical display in any one of the first to fifth aspects.

[0013] The antiglare substrate of the seventh aspect is preferably used in any one of the first to fifth aspects as a protective case for an exhibit.

[0014] The method for manufacturing an anti-glare substrate according to aspect 8 of the present invention is a method for manufacturing an anti-glare substrate according to any one of aspects 1 to 7, and is characterized by comprising the steps of: preparing a substrate having a main surface, including the glass substrate; adjusting the thickness of the substrate to 0.05 mm or more and 1 mm or less; and forming the uneven portion on the main surface of the substrate so that the arithmetic mean height Sa of the contour curved surface is 0.1 μm or more and 0.5 μm or less.

[0015] In the method for producing an antiglare substrate of aspect 9, in accordance with aspect 8, the substrate preferably consists of the glass substrate alone.

[0016] In the method for manufacturing an antiglare substrate of aspect 10, in aspect 8 or aspect 9, it is preferable that the main surface of the substrate is the main surface of the glass substrate, and the uneven portion is formed by performing a frost treatment on the main surface of the glass substrate. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an antiglare substrate and a method for manufacturing the same that can suppress both the reflection of external light and the deterioration of visual clarity and have excellent visibility. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view showing an antiglare substrate according to a first embodiment of the present invention. [Figure 2] 2(a) to 2(c) are schematic cross-sectional views illustrating an example of a method for manufacturing an antiglare substrate according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a schematic cross-sectional view showing an antiglare substrate according to a first modified example of the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an antiglare substrate according to a second modified example of the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0020] (Anti-glare board) (First embodiment) FIG. 1 is a schematic cross-sectional view showing an antiglare substrate according to a first embodiment of the present invention.

[0021] The antiglare substrate 1 is a substrate that is provided with antiglare properties, which suppress reflection of external light, etc. The antiglare substrate 1 has a glass substrate. More specifically, in this embodiment, the antiglare substrate 1 is made of only a glass substrate. The antiglare substrate 1 may have a configuration in which an antiglare film is provided on a glass substrate.

[0022] In this embodiment, the antiglare substrate 1 has a flat, rectangular shape. However, the shape of the antiglare substrate 1 is not limited to the above. The shape of the antiglare substrate 1 may be, for example, a flat plate shape with a circular or polygonal outline, a shape obtained by entirely curving a flat substrate, or a spherical or aspherical lens shape. It is desirable that the thickness of the antiglare substrate 1 is uniform. However, the antiglare substrate 1 may have a shape in which the thickness varies depending on the location.

[0023] The glass substrate in the antiglare substrate 1 is made of alkali-free glass. The material of the glass substrate is not limited to the above, and other silicate-based glasses such as aluminosilicate glass, alkali-containing aluminosilicate glass, borosilicate glass, lithium silicate glass, and soda-lime silicate glass can also be used. Here, silicate-based glass refers to glass containing 10 mass % or more of SiO2 in its glass composition.

[0024] The antiglare substrate 1 has a first main surface 1a and a second main surface 1b. The first main surface 1a and the second main surface 1b face each other. The first main surface 1a and the second main surface 1b are the surfaces of the antiglare substrate 1. The first main surface 1a is the main surface of the antiglare substrate 1 of the present invention. In this embodiment, an uneven portion 2 is provided over the entire surface of the first main surface 1a. The first main surface 1a has antiglare properties due to the uneven portion 2. It is sufficient that the uneven portion 2 is provided on at least a part of the first main surface 1a.

[0025] Of the first main surface 1a and the second main surface 1b of the antiglare substrate 1, only the first main surface 1a is provided with the concave-convex portion 2. However, the antiglare substrate 1 may also have the concave-convex portion 2 on both the first main surface 1a and the second main surface 1b.

[0026] This embodiment is characterized in that the thickness of the antiglare substrate 1 is 0.05 mm or more and 1 mm or less, and the arithmetic mean height Sa of the contour curved surface of the concave-convex portion 2 of the first principal surface 1a is 0.1 μm or more and 0.5 μm or less. This makes it possible to suppress both the reflection of external light and the deterioration of visual clarity, resulting in excellent visibility. This will be explained in detail below.

[0027] The antiglare substrate 1 has the uneven portion 2, which provides the antiglare substrate 1 with antiglare properties that suppress reflection of external light. On the other hand, if the antiglare substrate 1 has the uneven portion 2 and the surface of the antiglare substrate 1 is rough, the clarity of the image seen through the antiglare substrate 1 tends to deteriorate. In response to this, the present inventors have found that when the arithmetic mean height Sa of the contour curved surface of the uneven portion 2 on the first main surface 1a of the antiglare substrate 1 is set to 0.1 μm or more and 0.5 μm or less, the thinner the thickness of the antiglare substrate 1, the better the visual clarity can be.

[0028] Specifically, by making the thickness of the antiglare substrate 1 1 mm or less, it is possible to suppress deterioration of visual clarity, and by making the thickness of the antiglare substrate 1 0.05 mm or more, the antiglare substrate 1 is less likely to break.

[0029] The "arithmetic mean height Sa of a contour surface" is a parameter defined by ISO 25178, which is a parameter obtained by expanding a measured cross-sectional curve showing the cross-sectional shape of irregularities into a surface. Specifically, the arithmetic mean height Sa of a contour surface can be calculated as Sa = (Σ|Zn|) / n, which is the average of the absolute values of the heights Zn of each point on the surface relative to the average plane in a specified three-dimensional region. In this specification, the "arithmetic mean height Sa of a contour surface" may also be simply referred to as "arithmetic mean height Sa."

[0030] Preferred configurations of the present invention are described below. The arithmetic mean height Sa of the concave-convex portion 2 on the first main surface 1a of the antiglare substrate 1 is preferably greater than 0.1 μm, more preferably 0.2 μm or greater, and even more preferably 0.25 μm or greater. This effectively suppresses reflection of external light. On the other hand, the arithmetic mean height Sa is preferably 0.45 μm or less. In this case, the arithmetic mean height Sa of the concave-convex portion 2 is sufficiently small, making the antiglare substrate 1 less susceptible to damage.

[0031] The thickness of the antiglare substrate 1 is preferably 0.8 mm or less, more preferably 0.6 mm or less, even more preferably 0.5 mm or less, even more preferably 0.4 mm or less, and even more preferably 0.3 mm or less, thereby effectively suppressing deterioration of visual clarity.

[0032] The kurtosis Sku of the contour curved surface in the concave-convex portion 2 of the antiglare substrate 1 is preferably 0 or greater, and more preferably 0.2 or greater. This effectively suppresses the reflection of external light. In addition, it is possible to more reliably suppress the reflection of external light and the deterioration of visual clarity. In this specification, the "kurtosis Sku of the contour curved surface" may also be referred to simply as "kurtosis Sku."

[0033] The skewness Ssk of the contoured curved surface of the concave-convex portion 2 of the antiglare substrate 1 is preferably less than 0, and more preferably -0.3 or less. This effectively suppresses the reflection of external light. In addition, it is possible to more reliably suppress the reflection of external light and the deterioration of visual clarity. In this specification, the "skewness Ssk of the contoured curved surface" may also be referred to simply as "skewness Ssk."

[0034] The skewness Ssk and kurtosis Sku of the uneven portion 2 of the antiglare substrate 1 can be measured in accordance with ISO 25178.

[0035] An example of a method for manufacturing the antiglare substrate 1 according to the first embodiment will be described below.

[0036] (Method for manufacturing anti-glare substrate) 2(a) to 2(c) are schematic cross-sectional views illustrating an example of a method for manufacturing the antiglare substrate according to the first embodiment.

[0037] As shown in Figure 2(a), a substrate 3 consisting of only a glass substrate is prepared. The substrate 3 has a first main surface 3a and a second main surface 3b. The first main surface 3a and the second main surface 3b face each other. The first main surface 3a is the main surface of the substrate in the manufacturing method of the present invention.

[0038] 2(b), the thickness of the substrate 3 is adjusted to be 0.05 mm or more and 1 mm or less. The thickness of the substrate 3 may be adjusted by polishing the substrate 3, for example.

[0039] Next, a protective film 4 is attached to the second main surface 3b of the substrate 3. Next, an etching process is performed on the first main surface 3a of the substrate 3. Specifically, the substrate 3 is immersed in, for example, a hydrogen fluoride solution. This causes the first main surface 3a to be etched. By performing the etching process, dirt adhering to the first main surface 3a is removed. However, this etching process is not necessarily performed.

[0040] 2(c), the concave-convex portion 2 is formed on the first main surface 3a of the substrate 3 so that the arithmetic mean height Sa of the contour curved surface is 0.1 μm or more and 0.5 μm or less. Specifically, the first main surface 3a is subjected to a frost treatment.

[0041] More specifically, a fluid containing particles is sprayed onto the first main surface 3a of the substrate 3 to cause collision, and then the substrate 3 is immersed in a mixed solution containing hydrogen fluoride or the like. By colliding the fluid with the first main surface 3a, microcracks are formed on the first main surface 3a. By the subsequent immersion, the unevenness 2 is formed on the first main surface 3a. Note that the fluid may be, for example, a fluid mixed with water and alumina particles. The mixed solution may be, for example, a mixed solution containing hydrogen fluoride and potassium fluoride.

[0042] Next, an etching treatment is performed on the first main surface 3a of the substrate 3. Specifically, the substrate 3 is immersed in, for example, a hydrogen fluoride solution. After the etching treatment, the protective film 4 is peeled off from the second main surface 3b. In this manner, the antiglare substrate 1 shown in FIG. 1 is obtained. However, the etching treatment after the frost treatment is not necessarily performed.

[0043] The thickness of the substrate 3 may be adjusted after the first main surface 3a is provided with the concave-convex portion 2. In this case, for example, the second main surface 3b side may be polished.

[0044] In the first embodiment, the uneven portion 2 is provided over the entire surface of the first main surface 1a of the antiglare substrate 1. It is sufficient that the uneven portion 2 is provided over at least a portion of the first main surface 1a of the antiglare substrate 1. An example in which the uneven portion 2 is provided over a portion of the first main surface 1a is shown in a first modified example of the first embodiment.

[0045] (Anti-glare board) (First Modification) FIG. 3 is a schematic cross-sectional view showing an antiglare substrate according to a first modified example of the first embodiment.

[0046] The first main surface 11a of the antiglare substrate 11 has an uneven portion 2 and an unprocessed portion 15. The unprocessed portion 15 is a portion that has not been processed to provide the uneven portion 2. In this modified example, as in the first embodiment, it is possible to suppress both the reflection of external light and the deterioration of visual clarity, thereby achieving excellent visibility.

[0047] The uneven portion 2 is preferably provided over 1% or more of the area of the first main surface 11a of the antiglare substrate 11, more preferably over 30% or more, and even more preferably over 50% or more. The uneven portion 2 is not provided on the second main surface 1b. Therefore, the entire surface of the second main surface 1b is the unprocessed portion 15.

[0048] When manufacturing the antiglare substrate 11, for example, a protective film or the like may be attached to the area other than the area where the concave-convex portion 2 is to be formed, and then a frost treatment may be carried out.

[0049] As in this modification and the first embodiment, the antiglare substrate preferably consists of only a glass substrate. In this case, it is not necessary to provide an antiglare layer on the glass substrate. This increases productivity. In addition, there is no variation in the thickness of the antiglare layer provided on the glass substrate. This reduces the variation in the thickness of the antiglare substrate. This effectively reduces reflections when the concave-convex portion is provided.

[0050] In the present invention, the anti-glare substrate may have an anti-glare layer provided on the glass substrate, as shown in the second modified example of the first embodiment.

[0051] (Second Modification) FIG. 4 is a schematic cross-sectional view showing an antiglare substrate according to a second modified example of the first embodiment.

[0052] Antiglare substrate 21 has glass substrate 23 and antiglare film 26. Antiglare film 26 is provided on glass substrate 23. First main surface 21a of antiglare substrate 21 is the surface of antiglare film 26. More specifically, first main surface 21a is the surface of antiglare film 26 that faces the surface in contact with glass substrate 23. Examples of materials that can be used for antiglare film 26 include silicon oxide.

[0053] The uneven portion 2 is provided on the anti-glare film 26. The thickness of the anti-glare substrate 21 is the total thickness of the glass substrate 23 and the anti-glare film 26.

[0054] In this modification, as in the first embodiment, the thickness of antiglare substrate 21 is 0.05 mm or more and 1 mm or less, and the arithmetic mean height Sa of the contour curved surface of concave-convex portion 2 of first principal surface 21a is 0.1 μm or more and 0.5 μm or less. This makes it possible to suppress both the reflection of external light and the deterioration of visual clarity, thereby achieving excellent visibility.

[0055] The substrate prepared to obtain antiglare substrate 21 of this modified example is a laminated substrate in which a film made of a dielectric or the like is provided on glass substrate 23. In this case, the main surface of the substrate in the manufacturing method of the present invention is the surface of the film. When preparing glass substrate 23 and a substrate having the film, the film may be formed on glass substrate 23 by, for example, sputtering, CVD, or vacuum deposition.

[0056] By forming the uneven portion 2 on the above film, it is possible to obtain the anti-glare film 26. When forming the uneven portion 2 on the dielectric film, for example, blasting or the like can be used.

[0057] In the present invention, a functional film may be provided on the first main surface of the antiglare substrate. The functional film here refers to a film having an optical function, a function to prevent adhesion of dirt, etc. An example in which a functional film is provided will be shown below with reference to FIG. 1.

[0058] For example, an antireflection film may be provided only on the first main surface 1a of the first and second main surfaces 1a and 1b of the antiglare substrate 1. Alternatively, the antireflection film may be provided only on the second main surface 1b, or may be provided on both the first and second main surfaces 1a and 1b.

[0059] The anti-reflection film may be, for example, a dielectric multilayer film. The dielectric multilayer film may be, for example, a multilayer film including a high-refractive index film having a relatively high refractive index and a low-refractive index film having a relatively low refractive index. Preferably, the dielectric multilayer film has high-refractive index films and low-refractive index films stacked alternately.

[0060] Examples of materials for the high refractive index film include niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum oxide, and aluminum nitride.

[0061] Examples of materials for the low refractive index film include silicon oxide, aluminum oxide, and magnesium fluoride.

[0062] The thickness of each layer constituting the antireflection film can be, for example, 1 nm or more and 500 nm or less. The thickness of each layer is preferably 2 nm or more, and more preferably 5 nm or more. On the other hand, the thickness of each layer is preferably 300 nm or less, and more preferably 200 nm or less.

[0063] The number of layers constituting the anti-reflection film is not particularly limited. The number of layers constituting the anti-reflection film is preferably two or more. On the other hand, the number of layers constituting the anti-reflection film is preferably eight or less. By setting the number of layers constituting the anti-reflection film within the above range, it is possible to obtain a film that has an effective anti-reflection function and can be easily formed.

[0064] The total thickness of the antireflection film is not particularly limited, but can be, for example, 50 nm or more and 1000 nm or less. The total thickness of the antireflection film is preferably 75 nm or more, and more preferably 100 nm or more. On the other hand, the total thickness of the antireflection film is preferably 750 nm or less, and more preferably 500 nm or less.

[0065] The anti-reflection film can be formed by, for example, a sputtering method, a CVD method, or a vacuum deposition method.

[0066] In the present invention, another film such as an antifouling film, a decorative film, or a decorative coating may be provided only on the first principal surface 1a of the first principal surface 1a and the second principal surface 1b of the antiglare substrate 1. Alternatively, the other film may be provided only on the second principal surface 1b, or may be provided on both the first principal surface 1a and the second principal surface 1b.

[0067] The antifouling film is a film for preventing fingerprints from adhering and for imparting water and oil repellency. The antifouling film preferably contains a fluorine-containing polymer containing silicon in the main chain. As the fluorine-containing polymer, for example, a polymer having an -Si-O-Si- unit in the main chain and a water-repellent functional group containing fluorine in the side chain can be used. The fluorine-containing polymer can be synthesized, for example, by dehydration condensation of silanol.

[0068] Examples of decorative films and decorative coatings include resin films made from polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polypropylene (PP), polyethylene terephthalate (PET), acrylic, urethane, fluorine-based resins, etc., metal foils, and laminates of these.

[0069] The anti-glare substrate 1 can suppress both the reflection of external light and the deterioration of visual clarity, and has excellent visibility. Therefore, the anti-glare substrate 1 is particularly suitable for use as a cover member for medical displays, which particularly require high levels of both the reflection of external light and visual clarity. The anti-glare substrate 1 is also particularly suitable for use as a protective case for exhibits. In this case, the exhibits can be protected while being kept clearly visible. Alternatively, the anti-glare substrate 1 can be used as a cover member for displays such as mobile phones, tablet devices, televisions, and digital signage, as well as for lighting.

[0070] Examples of visibility indices include Clarity (C), Distinctness of Image (DOI), and Sparkle (S). Hereinafter, the first main surface of the antiglare substrate, which has antiglare properties, may be referred to as the antiglare surface. The second main surface, which faces the antiglare surface, may be referred to as the opposing surface.

[0071] The reflection index value C is an index that indicates the degree to which external light is reflected. The lower the reflection index value C, the lower the degree to which external light is reflected, and the better the visibility.

[0072] The reflection index value C is the ratio of the luminance of the specular reflection component to the luminance of the total reflected light, obtained from the luminance distribution data of an image of a light source reflected on the antiglare surface of the antiglare substrate. In other words, the reflection index value C [%] = (luminance of the specular reflection component / luminance of the total reflected light) × 100 [%]. The luminance of the specular reflection component represents the luminance in the range of the half-width of the peak luminance.

[0073] The DOI is an index related to visual resolution or clarity. The higher the DOI, the clearer the image is visually and the better the visibility.

[0074] The clarity of image (DOI) is calculated based on pixel image data obtained by imaging a display both without and with an anti-glare substrate. More specifically, the luminance waveforms are obtained by analyzing each pixel image data. The clarity of image (DOI) is the ratio of the value calculated based on ASTM D5767 from the luminance waveform with the anti-glare substrate placed on the display to the value similarly calculated from the luminance waveform without the anti-glare substrate placed on the display.

[0075] More specifically, the value calculated based on ASTM D5767 is a value expressed by (Mm) / (M+m) where M is the average value of the maximum value in the luminance waveform and m is the average value of the minimum value. The value in the state where the anti-glare substrate is placed on the display is M. AG When the value when no anti-glare substrate is placed on the display is M0, the image clarity DOI [%] = (M AG / M0)×100[%].

[0076] The glare index value S indicates the degree to which RGB pixels or uneven brightness on a display or the like appear to flicker as multiple light spots. In other words, the glare index value S indicates the degree of sparkle. The lower the glare index value S, the lower the degree of glare and the better the visibility.

[0077] The glare index value S is calculated from the pixel luminance of the pattern mask in image data obtained by imaging the anti-glare substrate with a surface light source disposed on the opposing surface of the anti-glare substrate and a pattern mask disposed between the opposing surface and the surface light source. Specifically, the glare index value S is calculated by dividing the average value and standard deviation of the pixel luminance of the pattern mask in the image data by the average value. In other words, the glare index value S [%] = (standard deviation of pixel luminance of the pattern mask / average value of pixel luminance of the pattern mask) × 100 [%].

[0078] The image of the anti-glare substrate is taken using a CCD camera from a position facing the anti-glare surface, with the anti-glare surface of the anti-glare substrate and the top surface of the pattern mask included within the depth of field of the set permissible circle of confusion diameter.

[0079] (Example) The present invention will be described in more detail below based on specific examples. In the examples, the reflection index value C and the clarity of image DOI were evaluated. Note that the present invention is not limited to the following examples and can be modified appropriately within the scope of the present invention.

[0080] (Sample 1) First, a glass substrate having a first main surface and a second main surface was prepared. Next, the thickness of the glass substrate was reduced to 0.3 mm by polishing. Next, a protective film was attached to the second main surface of the glass substrate.

[0081] Next, the glass substrate was immersed in a 3 wt % hydrogen fluoride solution for 3 minutes to etch the first main surface, thereby removing any dirt adhering to the first main surface.

[0082] Next, a frost treatment was performed on the first main surface of the glass substrate. More specifically, a fluid mixture of water and alumina particles was sprayed onto the first main surface to cause collision. Thereafter, the glass substrate was immersed in a mixed solution containing hydrogen fluoride and potassium fluoride. The mixed solution contained 15% by weight of hydrogen fluoride and 15% by weight of potassium fluoride. The immersion temperature was 23°C, and the immersion time was 60 seconds. As a result, concave and convex portions were formed on the first main surface.

[0083] Next, the glass substrate was immersed in a 10 wt % hydrogen fluoride solution for 6 minutes to etch the first main surface. Next, the protective film was peeled off from the second main surface. In this way, an antiglare substrate was obtained.

[0084] (Sample 2) An antiglare substrate was obtained in the same manner as in Sample 1, except that the thickness of the glass substrate was adjusted to 0.5 mm by polishing.

[0085] (Sample 3) An antiglare substrate was obtained in the same manner as in Sample 1, except that the thickness of the glass substrate was adjusted to 1.1 mm by polishing.

[0086] (Surface roughness evaluation) The arithmetic mean height Sa of the unevenness of each sample was confirmed to be 0.1 μm or more and 0.5 μm or less using a laser microscope. In addition, surface roughness parameters other than the arithmetic mean height Sa of the unevenness of each sample were measured. Note that in this specification, the "root mean square height Sq of the contoured surface," "maximum height Sz of the contoured surface," "maximum peak height Sp of the contoured surface," and "maximum valley depth Sv of the contoured surface" may also be referred to simply as "root mean square height Sq," "maximum height Sz," "maximum peak height Sp," and "maximum valley depth Sv."

[0087] The surface roughness parameters to be measured, including arithmetic mean height Sa, root mean square height Sq, skewness Ssk, kurtosis Sku, maximum height Sz, maximum peak height Sp, and maximum valley depth Sv, were measured using a laser microscope (Keyence Corporation, "VK-X250"). Each surface roughness parameter was measured in accordance with ISO 25178. Measurement of each surface roughness parameter was performed over a measurement area of 32 μm × 24 μm, with the number of acquired data points set to 1024 × 768 pixels and the reference length set to 1 / 5 of the measurement area.

[0088] The surface roughness parameters of the uneven portions of each sample were similar. Therefore, the parameters of sample 1 are shown in Table 1 as a representative.

[0089] [Table 1]

[0090] (Evaluation of visibility parameters) The reflection index value C and the distinctness of image DOI of Samples 1 to 3 were evaluated.

[0091] The reflection index value C was measured using an SMS-1000 (manufactured by Display-Messtechnik & Systeme) in the reflection distribution measurement mode. First, an immersion liquid was applied to the second principal surface of a sample anti-glare substrate, and the second principal surface was attached to black glass. The refractive index of the immersion liquid was 1.53. Next, a line light source and a photodetector were placed opposite the first principal surface of the anti-glare substrate. The incident angle of light from the line light source was 3°. The focal length of the photodetector lens was 16 mm. The distance between the photodetector lens and the position on the first principal surface of the anti-glare substrate where light was irradiated from the line light source was 410 mm. Then, the reflection index value C [%] = (luminance of specular reflection component / luminance of total reflected light) × 100 [%] was calculated using the SMS-1000 software from the luminance distribution data of the image of the light source reflected on the first principal surface of the anti-glare substrate.

[0092] The DOI was measured using the SMS-1000 in DOI measurement mode. Images of the display were taken with and without an anti-glare substrate placed on the display. From the pixel image data obtained, the DOI [%] = (M AG / M0) × 100[%] was calculated.

[0093] The evaluation results of Samples 1 to 3 are shown in Table 2.

[0094] [Table 2]

[0095] As shown in Table 2, the glare index value C for all of Samples 1 to 3 was low, at 2.0% or more and 2.1% or less. This shows that external light glare was effectively suppressed regardless of the thickness of the antiglare substrate. On the other hand, Sample 3, which was 1.1 mm thick, had a low DOI of 8.7%, making it visually unclear. In contrast, Sample 2, which was 0.5 mm thick, had a high DOI of 25.3%. Sample 1, which was 0.3 mm thick, had a higher DOI of 31.1%. As can be seen from these results, visual clarity is improved when the antiglare substrate thickness is 1 mm or less.

[0096] (Second embodiment) The configuration of the second embodiment of the present invention will be described below with reference to FIG.

[0097] The second embodiment differs from the first embodiment in the range of the thickness of the antiglare substrate. Except for the above, the antiglare substrate of the second embodiment has the same configuration as the antiglare substrate 1 of the first embodiment.

[0098] As described above, the anti-glare substrate has the uneven portion 2, which provides the anti-glare substrate with anti-glare properties that suppress reflection of external light. On the other hand, if the anti-glare substrate has the uneven portion 2 and the surface of the anti-glare substrate is rough, glare tends to be more noticeable. In response to this, the present inventors have found that when the arithmetic mean height Sa of the contour curved surface of the uneven portion 2 on the first main surface 1a of the anti-glare substrate is set to 0.1 μm or more and 0.5 μm or less, the thicker the anti-glare substrate is, the more effectively glare can be suppressed.

[0099] The second embodiment is characterized in that the thickness of the antiglare substrate is 0.4 mm or more, and the arithmetic mean height Sa of the contour curved surface of the concave-convex portion 2 on the first principal surface 1a is 0.1 μm or more and 0.5 μm or less. This makes it possible to suppress both the reflection of external light and glare, resulting in excellent visibility.

[0100] The antiglare substrate of the second embodiment can be suitably used as a cover member for a medical display or a protective case for an exhibit, similar to the first embodiment, or as a cover member for a display such as a mobile phone, a tablet terminal, a television, or a digital signage, or for lighting.

[0101] The second embodiment can also adopt the configurations of the first and second modifications of the first embodiment and the preferred ranges of each parameter other than the thickness, or a configuration in which an anti-reflection film, an anti-fouling film, a decorative film, a decorative coating, or the like is provided.

[0102] In the second embodiment, the thickness of the antiglare substrate is preferably 0.5 mm or more, and more preferably 1.1 mm or more. This allows for effective suppression of glare. On the other hand, the thickness of the antiglare substrate is preferably 2.0 mm or less. In this case, it is possible to promote miniaturization of components in which the antiglare substrate is used.

[0103] When obtaining this antiglare substrate, for example, in the step of adjusting the thickness of substrate 3 shown with reference to Fig. 2(a), the thickness of substrate 3 may be adjusted to 0.5 mm or more. The steps other than the step of adjusting the thickness of substrate 3 may be performed in the same manner as in the case of obtaining antiglare substrate 1 according to the first embodiment.

[0104] (Example) The evaluation of the glare index value S for the above samples 1 to 3 is shown below.

[0105] (Glare index value S evaluation) The glare index value S was measured using an SMS-1000 measuring device in sparkle measurement mode. First, a pattern mask was placed on a surface light source. Next, an antiglare substrate (sample) was placed on the pattern mask. Specifically, the antiglare substrate was positioned so that the second of its first and second main surfaces was facing the pattern mask. A CCD camera was placed opposite the first main surface of the antiglare substrate. The CCD camera used had a pixel count of 1296 × 966, a 1 / 3-inch sensor size, a pixel size of 3.75 μm × 3.75 μm, and a lens focal length of 100 mm. The lens aperture diameter of the CCD camera was set to 4.5 mm, the magnification ratio was set to 1:1, and the permissible circle of confusion diameter was set to 53 μm. The CCD camera was positioned so that the top surface of the pattern mask was located at the focal point of the lens.

[0106] The anti-glare substrate was photographed using a CCD camera, and the glare index value S [%] = (standard deviation of pixel luminance of pattern mask / average value of pixel luminance of pattern mask) × 100 [%] was calculated using the SMS-1000 software.

[0107] The evaluation results for Samples 1 to 3 are shown in Table 3. The evaluation results for the reflection index value C are also shown.

[0108] [Table 3]

[0109] As shown in Table 3, the glare index value C is low, at 2.0% or more and 2.1% or less, for all of Samples 1 to 3. This shows that external light glare is effectively suppressed regardless of the thickness of the antiglare substrate. On the other hand, Sample 1, which is 0.3 mm thick, has a glare index value S of 2.66%. In contrast, Sample 2, which is 0.5 mm thick, has a low glare index value S of 2.34%. Sample 3, which is 1.1 mm thick, has an even lower glare index value S of 1.69%. As can be seen from these results, glare is effectively suppressed when the thickness of the antiglare substrate is 0.4 mm or less. [Explanation of symbols]

[0110] 1...Anti-glare substrate 1a, 1b...first and second principal surfaces 2...Uneven part 3...Substrate 3a, 3b...first and second principal surfaces 4. Protective film 11...Anti-glare substrate 11a...first principal surface 15…Unprocessed part 21...Anti-glare substrate 21a...first principal surface 23...Glass substrate 26...Anti-glare film

Claims

1. An antiglare substrate having a main surface and having antiglare properties on the main surface, A glass substrate is provided, The thickness is 0.05 mm or more and 1 mm or less, An antiglare substrate, wherein an uneven portion is provided on at least a part of the main surface, and the arithmetic mean height Sa of the contour curved surface of the uneven portion is 0.1 μm or more and 0.5 μm or less.

2. The antiglare substrate according to claim 1 , which consists solely of the glass substrate.

3. 2. The antiglare substrate according to claim 1, wherein the glass substrate is made of alkali-free glass.

4. The antiglare substrate according to claim 1 , wherein the kurtosis Sku of the contour curved surface of the concave-convex portion is 0 or more.

5. The antiglare substrate according to claim 1 , wherein the skewness Ssk of the contour curved surface of the concave-convex portion is less than 0.

6. The antiglare substrate according to claim 1, which is used as a cover member for a medical display.

7. 10. The antiglare substrate according to claim 1, which is used as a protective case for an exhibit.

8. A method for producing the antiglare substrate according to claim 1, comprising: providing a substrate having a major surface, the substrate including the glass substrate; adjusting the thickness of the substrate to 0.05 mm or more and 1 mm or less; forming the concave-convex portion on the main surface of the substrate so that the arithmetic mean height Sa of the contour curved surface is 0.1 μm or more and 0.5 μm or less; A method for manufacturing an antiglare substrate, comprising:

9. The method for producing an antiglare substrate according to claim 8 , wherein the substrate consists of the glass substrate alone.

10. the main surface of the substrate is the main surface of the glass substrate, The method for manufacturing an antiglare substrate according to claim 8 , wherein the concave-convex portion is formed by performing a frost treatment on the main surface of the glass substrate.

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